MADISON - State roads officials pledged earlier this year that they would know by July just how bad the highway conditions are across Wisconsin and where to prioritize repairs.

But on Friday, amid a legislative impasse over roads funding, Department of Transportation officials delayed the release of their estimates until late August.

The agency’s figures have previously shown improving conditions for the state’s busiest roads and deterioration across the rest of the highway network. About 78.8 percent of non-major highways were rated fair or better in 2015, falling below the Department of Transportation’s goal of 80 percent for the first time since at least 2010.

A recent audit of the Department of Transportation also revealed a stark divide in the quality of pavement conditions geographically. Highways spanning the state's eastern counties were rated much better than western and northern roads.

Winnebago and Ozaukee counties in eastern Wisconsin had the top-rated highways, with 93 percent rated better than fair. By comparison, just 26 percent of highways met that rating in Pepin County, southwest of Eau Claire.

USA TODAY NETWORK-Wisconsin first requested the agency’s 2016 road quality estimates in January. At the time, agency officials said the figures were still being compiled and would be released in June or July. They called the information "key to monitoring and assessing pavement conditions and allocating resources as needed, so that we can best determine which segments of roadway to include in our six-year highway improvement program."

After the news organization again requested the estimates this month, the department revised its release date to late August. Agency officials did not immediately respond to a request for an explanation of the delay.

The Department of Transportation specifically tracks the condition of "backbone" and "non-backbone" roads as part of agency performance measures. "Backbone" roads, such as Interstates 39, 41, 43, 90 and 94, represent about 13 percent of the state's 12,000-mile highway network. They carry about half of the network's estimated traffic and more than 85 percent of its freight traffic.

While agency estimates show the pavement quality of "non-backbone" highways gradually worsened from 2012 to 2015, the condition of "backbone" streets steadily improved well above state goals. About 97.6 percent of backbone roads were rated fair or better in 2015. The state's goal is 90 percent.

Department of Transportation spokeswoman Patty Mayers said in January that the agency had prioritized repairs to "backbone" highways "in recognition of its importance to the state’s economy with respect to businesses and the traveling public."

Some legislators representing rural communities, such as Rep. Travis Tranel, R-Cuba City, have advocated in recent years for greater funding of "non-backbone" roads.

"We have not seen any significant investment in rural roads in far too long," Tranel urged his colleagues in January as this year's state budget debate started to heat up. "Some of our town roads have deteriorated to the point where farmers can no longer drive their tractors down them at 20 miles per hour."

Republican lawmakers who control Wisconsin’s state government have been unable to agree on roads funding this year, delaying a new two-year state budget a month beyond its June 30 deadline. Previous funding levels remain until a new budget is approved.

The impasse has focused on borrowing levels. Assembly leaders have opposed funding repairs through more borrowing, even if that means hiking fees or gas taxes, or introducing tolls to maintain repair plans. Senate leaders and Gov. Scott Walker have advocated for more borrowing and opposed the Assembly’s proposals to boost revenue.

Last week, Assembly leaders endorsed a compromise offered by Walker that would reduce borrowing levels by eliminating a proposed income tax cut and funnel more money to road repairs. However, it remains unknown whether the compromise has enough support to pass the Senate.

Keegan Kyle is an investigative reporter for USA TODAY NETWORK-Wisconsin. He can be reached at kkyle@gannett.com. Follow him on Twitter @keegankyle.